Japanese Patent Application Laid-Open (JP-A) No. 2004-009757 discloses a vehicle rear portion structure in which a parcel member, that connects rear wheel house portions, is provided at the top surface portions of the rear wheel house portions that are formed integrally with the left and right vertical wall portions of a rear floor panel.
Here, in a structure in which a parcel member is connected to the top surface portions of the left and right rear wheel house portions, the parcel member is substantially joined by pins to the rear wheel houses, and hardly contributes at all to the effect of improving the vehicle rigidity between the left and right rear wheel house portions. Note that joining by pins is a method of joining in which the joined region rotates when horizontal force is applied.
Accordingly, a parcel member that is substantially joined by pins to rear wheel houses hardly resists at all shearing deformation in the vehicle transverse direction. (Refer to JP-A No. 2004-009757.)